A circuit board having a metallic plate as a substrate and a flexible circuit board is disclosed in Japanese Patent Application Publication No. 2003-51651. The flexible circuit board is bonded on the metallic plate directly so that the circuit board has excellent heat conductivity and high rigidity. The flexible circuit board is made of thermoplastic resin. The circuit board is used, for example, for a meter board (i.e., a combination meter) in an instrument panel of an automotive vehicle. In this case, the circuit board has following problems.
Although the meter board of the vehicle works as a meter, it is required for the meter board to have a novel and impressive design. Therefore, each meter board has a different design corresponding to a type of the vehicle.
In general, it is required for the meter board to become larger, because of the design. For example, positioning of a motor for driving an indicator and an illumination lamp for the indicator is determined on the basis of the design; and therefore, the meter board becomes larger. Further, on the meter board, a control circuit for controlling the motor and the lamp is mounted. Specifically, the control circuit is mounted on an unused space in the meter board.
To comply with both conditions of the large meter board and the positioning of the control circuit, the circuit board includes multiple flexible circuit boards mounted on the metallic plate. Therefore, the area of the flexible circuit board becomes larger. Accordingly, a manufacturing cost becomes higher. Further, since the meter board has a different design corresponding to a type of the vehicle, so that a man-hour for designing the circuit board becomes larger.